GASTEROPODA. 43 



Length, f ths of an inch. 



Locality. Coralline Crag, near Orford. 



The specimen figured was found by myself, and Mr. Bell has very recently obtained 

 several more from the same place. There is a considerable difference among the 

 specimens, some being more elongated than others ; the shorter are strongly ribbed 

 on the body whorl, while on the longer the ribs become nearly obsolete. On the last 

 volution the whorls are very slightly shouldered, and the sinus is broad and shallow. 

 Clavattda concinnata, 'Crag. Moll.,' vol. i, p. 61, Tab. VII, fig. 11, a, b, are probably 

 varieties of this species. This is quite distinct from PI. decussata, Lam., as also from 

 PI. decussata of Couthouy. Phaphitoma plicatella, Jan., is closely allied, but seems to 

 have fewer ribs. 



Pleurotoma pyramidalis, Strom. Supplement, Tab. Ill, fig. 9, a, b, Tab. VII, fig. 22. 



Localities. Red Crag, Butley. Pluvio-marine Crag, Thorpe, in Suffolk {Bell). 

 Upper Glacial, Bridlington. Post-glacial, March and Kelsea Hill. 



The specimen of this well-known northern shell represented in fig. 9 of Tab. Ill is 

 one found by Mr. Bell in the Red Crag of Butley ; and that in the fig. 22 of Tab. VII 

 is one of a suite from March found by Mr. Harmer. They differ slightly, but may both, 

 I think, be referred to this species. The Crag shell has the body whorl smooth, but 

 there are indications of longitudinal riblets on the upper volutions. I cannot see any 

 spiral striae, but these may be obliterated by attrition. Some of the March specimens are 

 perfectly smooth without appearing to have undergone much wear, but in others faint 

 traces of riblets on the lower whorl are apparent. A specimen from Bridlington is in the 

 British Museum, and it is given from Kelsea Hill by Mr. Jeffreys. The species is given 

 from Thorpe in Suffolk by Mr. Bell in 'Ann. and Mag. of Nat. Hist.' for September, 1870. 



Pleurotoma bicarinata? Couth. Supplement, Tab. VI, fig. 17. 



Locality. Red Crag, Butley. 



The specimen figured was found by myself at Butley. It very much resembles 

 P. violacea of Meig. and Ad., but seems still closer to bicarinata, Couth., as there are 

 two very distinct carinas on the whorls. 



Many of the forms of Pleurotoma, both those in the Crag and those living in British 

 and Northern seas, run so much into each other, and are, withal, so inconstant in their 

 characters, even among a group of individuals of apparently the same species, that I feel 

 the greatest difficulty in assigning specific names, and I have therefore placed a note of 

 interrogation against the name of this species. 



